id:A074143 - OEIS Search Results

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a(1) = 1; a(n) = n * sum {a(k) | k < n}.

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8

1, 2, 9, 48, 300, 2160, 17640, 161280, 1632960, 18144000, 219542400, 2874009600, 40475635200, 610248038400, 9807557760000, 167382319104000, 3023343138816000, 57621363351552000, 1155628453883904000 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets`
	FORMULA	`a(n) = n^2a(n-1)/(n-1) for n > 2.` `a(n) = nceiling[n!/2] = n*A001710(n-1) = A001710(n+1)-A001710(n) = ceiling[A001563(n)/2] - Henry Bottomley (se16(AT)btinternet.com), Nov 27 2002`
	MAPLE	`seq(sum(mul(j, j=3..n), k=1..n), n=1..19); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 01 2007`
	CROSSREFS	`Sequence in context: A153390 A118341 A100427 this_sequence A052826 A115599 A000167` `Adjacent sequences: A074140 A074141 A074142 this_sequence A074144 A074145 A074146`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 28 2002`
	EXTENSIONS	`More terms from Henry Bottomley (se16(AT)btinternet.com), Nov 27 2002`

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Last modified December 11 12:57 EST 2009. Contains 170656 sequences.

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